Cell Biology Quiz
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Questions and Answers

What distinguishes transmembrane proteins from peripheral proteins?

  • Transmembrane proteins are always located outside the membrane.
  • Transmembrane proteins can form α helices that cross the lipid bilayer. (correct)
  • Transmembrane proteins do not interact with the lipid bilayer.
  • Transmembrane proteins are involved in intracellular signaling only.

    • What is the primary function of porins in bacterial membranes?

  • To form channels for the passage of specific molecules. (correct)
  • To mediate intracellular signaling.
  • To facilitate DNA replication.
  • To anchor cytoskeletal proteins.

    • Which statement about receptors in the plasma membrane is accurate?

  • They are necessary for protein synthesis.
  • They allow the cell to recognize chemical signals in the environment. (correct)
  • They degrade excess proteins within the cell.
  • They are exclusively glycoproteins.

    • The Golgi apparatus is primarily involved in which cellular process?

    <p>Modification, sorting, and packaging of proteins.</p> Signup and view all the answers

    Which technique is specifically used to locate proteins within cells?

    <p>Immunofluorescence.</p> Signup and view all the answers

    What structural component of the Golgi apparatus is made up of 5 to 8 cisternae?

    <p>Dictiosomes.</p> Signup and view all the answers

    What is indicated by the presence of multiple strands in a structure like bacteriorhodopsin?

    <p>It crosses the membrane multiple times forming channels.</p> Signup and view all the answers

    In SDS-PAGE, what is the primary purpose of the technique?

    <p>To separate proteins according to their mass.</p> Signup and view all the answers

    What is the primary direction of movement for kinesin along microtubules?

    <p>Towards the positive end</p> Signup and view all the answers

    What characterizes the structure of dyneins in terms of heavy and light chains?

    <p>2 to 3 heavy chains and 1 or more light chains</p> Signup and view all the answers

    Which component is crucial for the flexion of the axoneme in cilia and flagella?

    <p>Dynein motor activity</p> Signup and view all the answers

    Which protein undergoes glycosylation and is involved in the influenza virus?

    <p>Protein HA</p> Signup and view all the answers

    What is a key role of Cell Adhesion Molecules (CAMs) in tissues?

    <p>Establishing contact and interaction between cells</p> Signup and view all the answers

    Which of the following best describes the interaction mechanism between leukocytes and endothelial cells during extravasation?

    <p>Formation and rupture of intercellular contacts</p> Signup and view all the answers

    What is the role of oligosaccharides in protein processing?

    <p>They promote folding and stabilize proteins.</p> Signup and view all the answers

    Where does the phosphorylation of the mannose residue occur for lysosomal enzymes?

    <p>Trans-Golgi network</p> Signup and view all the answers

    Which transferase is specifically associated with the Trans-Golgi network?

    <p>Galactosyltransferase</p> Signup and view all the answers

    What could be the consequence of a mutation replacing asparagine in protein HA?

    <p>It would cause improper glycosylation.</p> Signup and view all the answers

    What happens to non-glycosylated Fibronectin by fibroblasts?

    <p>It is rapidly degraded by proteases.</p> Signup and view all the answers

    What is the purpose of the mannose-6-phosphate (M6P) receptor?

    <p>To sort lysosome-destined proteins specifically.</p> Signup and view all the answers

    What is a likely effect of antibiotic Tunicamycin on protein processing?

    <p>It blocks glycosylation.</p> Signup and view all the answers

    Which type of adhesion molecule connects cells through homophilic interactions?

    <p>Cadherins</p> Signup and view all the answers

    What is the consequence of a genetic defect in β 2 Integrin synthesis?

    <p>Leukocyte adhesion deficiencies</p> Signup and view all the answers

    Which of the following does NOT depend on Ca+2 for its function?

    <p>Integrins</p> Signup and view all the answers

    GAP junctions primarily consist of which type of protein?

    <p>Connexins</p> Signup and view all the answers

    Desmosomes are primarily associated with which class of adhesion molecules?

    <p>Cadherins</p> Signup and view all the answers

    What is the primary function of integrins in relation to the extracellular matrix (ECM)?

    <p>To facilitate cell-ECM adhesion</p> Signup and view all the answers

    What is a characteristic feature of collagen regarding its molecular structure?

    <p>It forms a triple helix structure</p> Signup and view all the answers

    What type of structural protein is laminin, and what is its primary role?

    <p>A multiadhesive protein forming part of the basal lamina</p> Signup and view all the answers

    Which of the following best describes the effect of a defect in the integrin cytosolic domain β subunit?

    <p>Inability to form stable clots, leading to hemorrhage</p> Signup and view all the answers

    Which statement about proteoglycans in the ECM is correct?

    <p>They consist of a protein core and multiple chain polysaccharides.</p> Signup and view all the answers

    In vertebrate tissue, what is the role of fibronectin?

    <p>To bind integrin receptors to the ECM</p> Signup and view all the answers

    What is a significant characteristic of collagen types I, II, and III in the extracellular matrix?

    <p>They collectively make up 80% of all collagen in vertebrates.</p> Signup and view all the answers

    What component exists as a cross-structured protein within the basal lamina?

    <p>Laminin</p> Signup and view all the answers

    What is the primary role of proteoglycans in the extracellular matrix?

    <p>Anchoring cells to the extracellular matrix</p> Signup and view all the answers

    Which statement best describes stem cells?

    <p>Cells that can generate differentiated cells indefinitely</p> Signup and view all the answers

    What process describes the interaction between endothelial cells?

    <p>Mechanotransduction</p> Signup and view all the answers

    Which of the following cell types are considered somatic cells?

    <p>Muscle and nerve cells</p> Signup and view all the answers

    What determines the fate of cell lineages?

    <p>Intrinsic and extrinsic factors</p> Signup and view all the answers

    What happens during terminal differentiation of a cell?

    <p>Cells become irreversibly specialized and typically cannot divide</p> Signup and view all the answers

    What is a precursor cell?

    <p>A stem cell that has limited differentiation potential</p> Signup and view all the answers

    What characterizes the process of cell lineage development?

    <p>It involves the history and response of cells to various factors</p> Signup and view all the answers

    Study Notes

    Exam Final 2024 Topics

    • Plasma Membrane: A phospholipid bilayer with embedded proteins. It regulates what enters and leaves the cell. Includes components like lysosomes, peroxisomes, rough and smooth endoplasmic reticulum, centrioles, cilia, centrosome, cytoplasm, microvilli, mitochondrion, ribosomes, nucleoplasm, nucleolus, nuclear pores, and nuclear envelope.

    Golgi Apparatus

    • Structure: A series of flattened sacs (cisternae) with associated vesicles. Has distinct cis (forming) and trans (maturing) faces. Also has associated tubules.
    • Functions: Glycosylation of proteins and lipids, protein modification, and packaging of secreted proteins into vesicles.

    Cytoskeleton

    • Actin Filaments (Microfilaments): Two-stranded helical polymers. Found in the cell cortex and involved in cell motility and contractility.
    • Microtubules: Long hollow cylinders made of tubulin protein. Crucial for intracellular transport, cilia, and flagella.
    • Intermediate Filaments: Rope-like fibers, composed of various intermediate filament proteins. Provide strength and mechanical support to cells. Keratin forms a large part of these fibers.

    Extracellular Matrix (ECM)

    • Composition: Composed of fibrous proteins (e.g., collagen, fibronectin), proteoglycans, and adhesive glycoproteins.
    • Function: Provides structural support, regulates cell signaling and binds cells together.

    Stem Cell/Apoptosis (Cell Birth, Lineage and Death)

    • Stem Cells: Unspecialized cells that can self-renew and differentiate into specialized cell types.
    • Apoptosis: Programmed cell death, a crucial process for tissue development and maintenance. Necrosis is the opposite, rapid lysis of the cell.
    • Lineage: Series of cell divisions from stem cells to differentiated cells; there are distinct stages in this process.

    Membrane Proteins

    • Transmembrane Proteins: Proteins that span the membrane and mediate transport of substance. Examples include: ion channels, integrin dimers and Glycoproteins
    • Peripheral Proteins: Proteins that sit on one side of the membrane interacting with membrane components indirectly only.

    Chemical Basics

    • Polar molecules: Soluble in polar solvents like water.
    • Nonpolar molecules: Insoluble in water; aggregate together.

    Phospholipids

    • Amphipathic: Both polar and nonpolar regions

    Fatty acids

    • Saturated: No double bonds.
    • Unsaturated: At least one double bond.

    Other Components of Membranes

    • Glycoproteins: Carbohydrates attached to proteins, increasing their hydrophilicity and stabilizing their conformation in the membrane.

    • Glucolipids (Glycolipids): Carbohydrates attached to lipids, increasing their hydrophilicity.

    Types of Membrane Proteins

    • Integral (Transmembrane): Domains that cross the membrane; mostly alpha helices or beta sheets.

    • Peripheral: Associated with one side of the membrane; may attach to membrane components.

    Steroids

    • Typical example is Cholesterol.
    • They are amphipathic, with a hydrophilic region and a hydrophobic region.

    Protein Classification (A.A)

    • Nonpolar R groups: Hydrophobic
    • Polar R groups: Hydrophilic
    • Negatively Charged R groups: Hydrophilic
    • Positively charged R groups: Hydrophilic

    Erythrocyte Membrane

    • Key structural proteins: Spectrin, Ankyrin, Actin, Tropomyosin, and Adducin, etc.

    Bacteriodopsin and Porins

    • Porins: Transmembrane proteins forming barrels that facilitate the passage of disaccharides and phosphates across the membrane.
    • Bacteriodopsin: Contains multiple alpha-helices that cross the membrane; transmembrane protein.

    Immunofluorescence (locating proteins inside the cell)

    • Method to visualize proteins inside a living sample. Includes direct and indirect immunofluorescence.

    Centrifugation Techniques

    • Differential centrifugation: Separates cellular components based on size and density.
    • Rate zonal centrifugation: Separates components based on density in a density gradient.

    SDS-polyacrylamide Gel Electrophoresis (SDS-PAGE)

    • Separates proteins based on size.

    Estimating Protein Molecular Weight

    • Using known molecular weight standards, plotting a graph of logarithm of molecular weight against relative migration allows estimating the unknown protein molecular weight.

    Gel Filtration Chromatography

    • Separates proteins based on size (large molecules elute first).
    • Separates based on molecular size of protein.
    • Separates by molecular size during the experiment

    Antibody techniques

    • ELISA: Method for detecting and quantifying a specific protein using antibodies.

    • Western Blot: Method for detecting a specific protein using antibodies that detects a target protein of interest.

    Immune response to blood groups

    • Antigens and Antibodies. The specific reactions between them result in different blood types.
    • Different blood groups based on their carbohydrate antigens.

    Glycosylation

    • Modifications of glycoproteins by carbohydrates in the endoplasmic reticulum and Golgi complex, which are important for stability and folding of proteins.

    Processing of N-linked oligosaccharide chains

    • Steps in enzymatic processes for modifying proteins using carbohydrates and their precursors

    Modifications of N-oligosaccharides

    • Localization of enzymes responsible for modifying N-oligosaccharides in the Golgi complex.

    Structure of Axonemes of Cilia and Flagella

    • Structure: Provides a basic picture demonstrating the different components of cilia and flagella to help understand their functions.

    Dynein and Kinesin (Microtubule associated proteins) , Motor Proteins

    • Kinesins: Motor proteins that move along microtubules towards the plus (+) end. Involved in anterograde transport (towards the cell periphery).
    • Dyneins: Motor proteins that move along microtubules towards the minus (-) end. Involved in retrograde transport (toward the cell body) in vesicular traffic, ciliary muscles and cellular movements.
    • Basic Structure of both proteins, particularly describing head, tails, and other structural regions associated with the proteins

    Intermediate filaments

    • Keratin and its involvement with the process of skin diseases (Epidermolysis bullosa simplex)
    • Structural and other important characteristics(properties) of intermediate filaments.

    Cytoskeleton II

    • Microtubules, their role in intracellular transport through cilia and flagella, and their structure (tubulin protein forming hollow cylinders) along with basic functions. MTOC (Microtubules-Organizing Center) also known as the centrioles (pair of centrioles forming a structure that looks like a perpendicular 'L').

    Dynamic Instability

    • Dynamic instability (growth and shrinkage): property of microtubules, with processes of catastrophe and rescue.

    Polarization of Epithelial Cells:

    • Process by which epithelial cells develop a polarized structure, including apical and basement membrane (basolateral).

    Mechanotransduction:

    • The process in which physical forces applied to a cell translate into intracellular signalling pathways and cellular responses. How mechanical stress is communicated to the internal cell.

    Golgi Apparatus

    • Cis face: The receiving face/entry point of the Golgi.
    • Trans face: The shipping/destination region of the Golgi.

    Peroxisome

    • Import system: Includes Pex proteins that direct proteins into peroxisomes.

    Mannose-6-Phosphate (M6P)

    • Targeting sequence: Directs enzymes to lysosomes through binding to M6P receptors.

    Other routes of M6P

    • Receptor-mediated endocytosis: How cells bring M6P-tagged proteins into the lysosomes, including the role of receptors, vesicles, clathrin, etc.

    Proteoglycans

    • Composition: Multiple glycosaminoglycans linked to a core protein. Form a network in cartilage, etc.

    Fibronectin

    • Structure and Function.

    Collagen

    • Composition, including the triple helix and its importance in the extra-cellular matrix.
    • Molecular structure of collagen type IV (basal lamina)

    Cell Birth, Lineage, and Death

    • Overview of cell birth from symmetric and asymmetric cell divisions, and how these processes influence cell lineages.

    Apoptosis

    • Morphological changes and role of proteins during the process of apoptosis.

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    Description

    Test your knowledge on key concepts in cell biology, including the functions and structures of proteins, organelles, and cellular processes. Explore the roles of transmembrane proteins, the Golgi apparatus, and the mechanics of motor proteins like kinesin and dyneins.

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